Over 60 countries which produce nautical charts also
produce a notice to mariners. About one third of these are
weekly, another third are bi-monthly or monthly, and the
rest irregularly issued according to need. For example, the United Kingdom Hydrographic Office issues weekly updates.

Information for the Notice to Mariners is contributed
by: the National Geospatial-Intelligence Agency (Department of Defense) for waters
outside the territorial limits of the United States; National
Ocean Service (National Oceanic and Atmospheric Administration,
Department of Commerce), which is charged
with surveying and charting the coasts and harbors of the
United States and its territories; the U.S. Coast Guard (Department of Homeland Security) which is responsible for the safety of life at sea and the establishment and operation of aids to navigation; and the Army Corps of Engineers (Department of Defense), which is charged with the
improvement of rivers and harbors of the United States. In
addition, important contributions are made by foreign hydrographic
offices and cooperating observers of all
nationalities.

The Notice consists of a page of Hydrograms listing
important items in the Notice, a chart correction
section organized by ascending chart number, a product catalog corrections section, a publications
correction section, a summary of broadcast
navigation warnings, and a page of additional miscellaneous information. It is the responsibility of users to decide which of their
charts and publications require correction.
Mariners are requested to cooperate in the correction of
charts and publications by reporting all discrepancies between
published information and conditions actually
observed and by recommending appropriate improvements. A reporting form is provided in the back of each
Notice to Mariners.

Issue No. 1 of each year contains important
information on a variety of subjects which supplements
information not usually found on charts and in navigational
publications. This information is published as Special Notice
to Mariners Paragraphs. Additional items considered
of interest to the mariner are also included in this Notice.

Much of the data
in the U.S. Notice to Mariners is obtained from foreign
notices.

Canada

In Canada, the Canadian Coast Guard (CCG) Notice to Mariners publication informs mariners of important navigational safety matters affecting Canadian Waters. This electronic publication is published on a monthly basis and can be downloaded from the Notices to Mariners (NOTMAR) Web site. The information in the Notice to Mariners is formatted to simplify the correction of paper charts and navigational publications.

The NOTMAR.gc.ca site is a free 24/7 service providing mariners with up-to-date safety advisories. It provides mariners with a quick and easy to use interface to access Notices to Mariners information. This system also generates weekly and monthly notification mailers, for its registered users. These on-line mail services provides the monthly Notices to Mariners publications as well as the weekly(section II - chart corrections) notices that advise the mariner of the notices that have been issued against their chart selections. These mail services simplify the process for registered clients to update their publications and charts as required under the Canada Shipping Act.

Summary of Corrections

A close companion to the Notice to Mariners is the Summary of Corrections. The Summary is published in five volumes. Each volume covers a major portion of the earth including several chart regions and many subregions. Volume 5 also includes special charts and publications corrected
by the Notice to Mariners. Since the Summaries contain cumulative corrections, any chart, regardless of its print date, can be corrected with the proper volume of the Summary and all subsequent Notice to Mariners.